Half Life 2 Skies

If you're talking about the 2D versions i'd suggest using Terragen in combination with some good old Photoshopping.

How big are the 2D skies? If they're standard 256x256, then look at these:

http://www.planethalflife.com/wadfather/

You can make the terrain and buildings in HL2 and people would hardly even notice the background stuff..

You could get your camera and find a building or something high to get on top of and take your own sky pics.

Stand and face north with your camera level to the horizon and take a pic. Then rotate and do it for north-east, then east, and so on until you get a pic of each major direction, 8 total. Make sure you overlap them by a couple of inches. Then angle your camera up about 45 degrees and take a 4 pics, north, east, south, and west. Then take one straight up.

The hard part is stitching them together. Get them into photoshop and blend them all together. Mikezilla could probably tell you more about this part.

All this may only work if you're mapping this final texture to a dome shape though you could probably make it fit a cube shape.

I personally don't like terragen because it's terrians are just too unrealistic without a good deal of photoshopping. They all have that instantly recognizable terragen look.

A tripod would be fairly essential for the above method.

http://%7boption%7d When I dabbled in skymaps, this tool proved fairly useful.

Quote from Fullauto

A tripod would be fairly essential for the above method.

Not really. As long as you overlap the edges of each picture, just a little photoshopping will do.

Skypaint is awesome, I remember asking for a serial on here awhile back haha, just type in 'park' works everytime. Really cool program and very easy to use.

Try Vue D'Esprit too, it's pretty good at skies/backdrops.

http://%7boption%7d

Vue d'Esprit is awesome, but usually i don't want all kinds of funky details on my skyline because those will look weird. And personally, i find that for 'just' skylines, Terragen works better. I wrote a tutorial on Terragen a while ago, let me look it up.